Sea Surface fCO2 measurements in the Indian and Southern Oceans obtained during MINERVE-33 associated to JGOFS/ANTARES-3 cruise
onboard the R.V. Marion-Durfresne (IPEV), 28/9-7/11/95 (Chief Scientist, P.Mayzaud, LEBEPM, Villefranche/Mer, FRANCE)
Prepared by N.Metzl and C.Brunet
Laboratoire de Biogeochimie et Chimie Marines (LBCM), UMR 7094 Institut Pierre Simon Laplace
Universite P. et M. Curie - Case 134
4, place Jussieu - 75252 PARIS Cedex 5 - FRANCE http://www.lbcm.jussieu.fr/
Method
The sea surface fugacity of CO2 (fCO2) was measured onboard the reasearch vessel Marion-Dufresne (IPEV) during the French JGOFS/ANTARES-3 by C. Brunet and C.
Grosbois (LBCM, Paris) in the frame of the project MINERVE-33. The fCO2 measurements technique has been described for other MINERVE cruises conducted during years 1990-1995 in the Indian and Southern Ocean (Poisson et al.,1993; Metzl et al. 1995, 1999). This instrumentation was also used by our group during the international at-sea intercomparison of fCO2 systems conducted in 1996 in the North-Atlantic (Kortzinger et al., 2000).
In short, sea surface water is continuously equilibrated using a "thin film" type equilibrator thermostated with surface seawater. The CO2 in the dried gas is measured with a non- dispersive infrared analyser (NDIR, Siemens Ultramat 5F). Standard gases for calibration (269.9, 349.7, 489.6 ppm) and atmospheric CO2 are measured every 7 hours. To correct measurements to in situ data, we used polynomials given by Weiss and Price (1980) for vapour pressure and by Copin-Montégut (1988, 1989) for temperature. On average, the temperature in the thermostated equilibrium cell was 1.00°C warmer than SST during MINERVE-33 cruise. Based on different cruises analysis, the oceanic fCO2 data are accurate to about ± 0.7 µatm. All parameters presented in this data-set correspond to the average of about 60 records made during 10 minutes.
During this cruise, problems have been identified for salinity on thermosalinographer records; therefore, when salinity is needed for calculating polynomials (for fCO2 corrections), the sea surface salinity has been reconstructed based on well-known T/S relations-ship in the
investigated region. This does not introduce significant errors on fCO2 corrections; however, salinity itself being subject to low accuracy, it has not been included in the data-file.
The fCO2 data obtained during MINERVE cruise have been included in synthesis studies of air-sea CO2 fluxes at regional scale in the SubAntarctic zone (Metzl et al., 1999), for constructing global scale pCO2 climatologies (Takahashi et al., 2002) and for comparing and/or validating ocean models (e.g. Louanchi et al., 1996; Metzl et al., 1998).
File description
The file MIN33CO2W.xls contains all the results of sea surface fCO2 measurements (and associated properties) made onboard during the cruise MINERVE-33. The columns of the file include: Date (dd/mm/yy, hh:mn), Latitude (degre.degre), Longitude (degree.degree), atmospheric pressure (mb), sea surface water fCO2 fugacity (µatm) normalized at 1atm, FCO2 (1013) and at local pressure, FCO2 (Patm), fluoresence (in relative units), temperature in the equilibrium cell (°C), sea surface temperature (°C). The first date, first line of the data set, is 28/09/95 at 04:04.
For more information or if you have questions concerning these data, please contact N.Metzl (metzl@ccr.jussieu.fr) or C.Brunet (brunet@ccr.jussieu.fr)
References:
Copin-Montégut, C., 1988. A new formula for the effect of temperature on the partial pressure of CO2 in seawater. Mar. Chem., 25, 29-37.
Copin-Montégut, C., 1989. A new formula for the effect of temperature on the partial pressure of CO2 in seawater. Corrigendum. Mar. Chem., 27, 143-144.
Kortzinger, A., L. Mintrop, D.W.R. Wallace, K.M. Johnson, C. Neill, B. Tilbrook, P. Towler, H.Y. Inoue, M.
Ishii, G. Shaffer, R.F. Torres Saavedra, E. Ohtaki, E. Yamashita, A. Poisson, C. Brunet, B. Schauer, C.
Goyet, G. Eischeid, The international at-sea intercomparison of fCO2 systems during the R/V Meteor Cruise 36/1 in the North Atlantic Ocean, Marine Chemistry, 2(2-4), 171-192., 2000.
Louanchi, F., N. Metzl, A. Poisson, 1996. Modelling the monthly sea surface fCO2 fields in the Indian Ocean.
Marine Chemistry, 55, 265-279.
Metzl, N., A.Poisson, F. Louanchi, C. Brunet, B. Schauer , 1995. Spatio-temporal distributions of air-sea fluxes of CO2 in the Indian and Antarctic Oceans: a first step. Tellus, 47B, 56-69.
Metzl, N., F.Louanchi and A.Poisson, 1998. Seasonal and interannual variations of sea surface carbon dioxide in the subtropical Indian Ocean. Marine Chem., 60, 131-146.
Metzl, N., B.Tilbrook, A.Poisson, 1999. The annual fCO2 cycle and the air-sea CO2 fluxes in the sub-Antarctic Ocean Tellus, 51B, 4, 849-861.
Poisson, A., N. Metzl, C. Brunet, B. Schauer, B. Brès, D. Ruiz-Pino and F. Louanchi, 1993. Variability of sources and sinks of CO2 and in the Western Indian and Southern Oceans during the year 1991. J. Geophys.
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Takahashi, T., S C. Sutherland, C. Sweeney, A.Poisson, N.Metzl, B.Tilbrook, N.Bates, R.Wanninkhof, R.A.
Feely, C.Sabine and J.Olafsson and Y. Nojiri, 2002. Global Sea-Air CO2 Flux Based on Climatological Surface Ocean pCO2, and Seasonal Biological and Temperature Effect. Deep Sea Res. II, Vol 49, N 9-10, 1601-1622.
Weiss, R.F. and B.A. Price, 1980. Nitrous oxide solubility in water and seawater. Marine Chem., 8, 347-359.
